EP0349404B1 - Gigantic liquid crystal display - Google Patents

Gigantic liquid crystal display Download PDF

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Publication number
EP0349404B1
EP0349404B1 EP89401805A EP89401805A EP0349404B1 EP 0349404 B1 EP0349404 B1 EP 0349404B1 EP 89401805 A EP89401805 A EP 89401805A EP 89401805 A EP89401805 A EP 89401805A EP 0349404 B1 EP0349404 B1 EP 0349404B1
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EP
European Patent Office
Prior art keywords
screen
liquid crystal
means according
crystal display
display
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EP89401805A
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German (de)
French (fr)
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EP0349404A1 (en
Inventor
François Morin
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Orange SA
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France Telecom SA
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/3147—Multi-projection systems
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F19/00—Advertising or display means not otherwise provided for
    • G09F19/12—Advertising or display means not otherwise provided for using special optical effects
    • G09F19/18—Advertising or display means not otherwise provided for using special optical effects involving the use of optical projection means, e.g. projection of images on clouds
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • G09F9/35—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being liquid crystals

Definitions

  • the present invention relates to a giant liquid crystal display device. It finds an application in the display of very large images (several square meters), images generally of the color video type. A fortiori, can we use the invention in less restrictive fields: alphanumeric display, still or slowly variable images, monochromatic, etc.).
  • Giant display devices can be produced either from cathode ray tubes or using a liquid crystal display.
  • the Eidophore type projector the heart of which is an oil film tube locally deformed by an electron beam.
  • This oil film thanks to its variable birefringence, causes a variation in contrast in the projection optical beam.
  • the Eidophore is the only system allowing video projection on a very large screen.
  • the assemblies of cathode ray tubes or liquid crystal displays have the disadvantage of having a "black grid” effect due to the junction of the various modules. They are not suitable for quality display.
  • modules with liquid crystal display have a heterogeneity of coloring due to the use of multiple colored mosaic filters (one per screen).
  • the eye being very sensitive to variations in color, the observer generally distinguishes very clearly the variations in coloring from one module to another, when displaying isochromic ranges.
  • the colored filters are located inside the cell to avoid the effects of parallax; as a result, they heat up under strong luminous flux, which causes a deterioration of the contrast of the display.
  • tri-tube cathode ray projectorsm are only suitable for medium surfaces (of the order of a square meter) and are of poor quality due to the spatial non-fixity of the image of the tube.
  • the superimposition of the three colors is generally imperfect.
  • the object of the present invention is precisely to remedy these drawbacks.
  • the invention covers the case where only one projection module is used, it is preferred to juxtapose a plurality of modules arranged in rows and columns, the images corresponding to these various modules being juxtaposed on the screen to form a unique image.
  • the liquid crystal display is of the active matrix type; it is for example with thin film transistors.
  • the liquid crystal displays are therefore monochrome, which avoids the presence of colored filters inside the display and, consequently, the risk of their heating and their degradation. Filters are on the observation screen. Their realization is thereby facilitated: disappearance of the constraints linked to compatibility with liquid crystals, and possibility of larger dimensions (colored elements of the order of a square millimeter on the projection screen) allowing production by printing works.
  • the projected images can be connected to the nearest pixel, thanks to an adjustable mechanical mounting of the projection modules: the connections between the projected modular images are then invisible.
  • the rear projection system leads to the design of autonomous screens which, thanks to a set of mirrors, can be of low thickness, therefore compact.
  • FIGS. 1 and 2 show a giant display device according to the invention.
  • This device comprises a screen E of very large dimensions, two rows of three projection modules MP, each associated with a first mirror M1 and a second mirror M2.
  • the assembly is carried by a chassis 6 which includes adjustment means, not shown, for the initial adjustment of the various modules with respect to on the screen.
  • a photosensitive cell C measures the light intensity emitted by each module and consequently controls the corresponding module to obtain the appropriate intensity.
  • FIG 3 illustrates in more detail the structure of a projection module.
  • a white light source S halogen or metal halide lamp
  • an aspherical condenser C a double Fresnel lens F
  • a first polarizer P1 a liquid crystal display A
  • a projection lens L L ' display is located in the object focal plane of this lens, the screen E being located in the image plane.
  • the second polarizer P2 is supposed to be pressed against the screen (see Fig. 4).
  • the Fresnel lamp-condenser-double lens assembly has the function of illuminating the display A at an obtuse angle, so that all the light passing through it converges at the center of the projection lens L. This thus optimizes the light output.
  • the projection lens L has a sufficient opening to avoid any chromatic aberration.
  • the liquid crystal display is preferably of the active matrix and thin film transistor (TFT) type.
  • TFT thin film transistor
  • Such a display leads to high contrast, makes it possible to obtain gray levels and accommodates a rate compatible with television signals.
  • the screen it can be in accordance with FIG. 4. It is located in the image plane of the projection lens and consists of a transparent supoprt 10 (glass or polycarbonate) having a front face 12 directed towards the observer 0 and a rear face 14. This last face is slightly frosted, in order to diffuse the light in a comfortable viewing angle (gain of the screen less than 6).
  • a transparent supoprt 10 glass or polycarbonate
  • This last face is slightly frosted, in order to diffuse the light in a comfortable viewing angle (gain of the screen less than 6).
  • On the rear face 14 are deposited mosaics of colored filters 16 in three primary colors, R, G, B (red, green, blue for example), either by a direct printing process ("offset” or serigraphy), or by collage of a color photographic film.
  • offset direct printing process
  • collage of a color photographic film.
  • the pixel distribution of the liquid crystal display is exactly that of the elementary color filters of the screen. In the illustrated case, this distribution is "triangular", or if desired, staggered.
  • the address lines remain horizontal, as usual, but the address columns have notches.
  • each pixel of the display is projected exactly on one of the colored filters of the screen.
  • Each display is controlled so that the projected image, which is only modulated in intensity, shows the desired image in color.
  • liquid crystal displays of 7 cm x 9 cm can be produced with a pitch of 250 ⁇ m; you can use a magnification of 10, which leads to modular images of 70 x 90 cm; the screen may include filters distributed in steps of 2.5 mm and have dimensions of 1.4 mx 2.7 m; there are thus two rows of three modular images; such a image therefore includes 560 lines of 360 triads, or 560 x 1080 pixels.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Business, Economics & Management (AREA)
  • Accounting & Taxation (AREA)
  • Marketing (AREA)
  • Liquid Crystal (AREA)
  • Projection Apparatus (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)

Description

La présente invention a pour objet un dispositif d'affichage géant à cristaux liquides. Elle trouve une application dans l'affichage d'images de très grandes dimensions (plusieurs mètres carrés), images généralement de type vidéo en couleur. A fortiori, peut-on utiliser l'invention dans des domaines moins contraignants : affichage alphanumérique, images fixes ou lentement variables, monochromatiques, etc.).The present invention relates to a giant liquid crystal display device. It finds an application in the display of very large images (several square meters), images generally of the color video type. A fortiori, can we use the invention in less restrictive fields: alphanumeric display, still or slowly variable images, monochromatic, etc.).

On peut réaliser des dispositifs d'affichage géants soit à partir de tubes cathodiques, soit à l'aide d'afficheur à cristaux liquides.Giant display devices can be produced either from cathode ray tubes or using a liquid crystal display.

Dans la première famille, il faut mentionner d'abord le projecteur de type Eïdophore, dont le coeur est un tube à film d'huile déformé localement par un faisceau d'électrons. Ce film d'huile, grâce à sa biréfringérence variable, provoque une variation de contraste dans le faisceau optique de projection. L'Eïdophore est le seul système permettant la projection vidéo sur très grand écran.In the first family, we must first mention the Eidophore type projector, the heart of which is an oil film tube locally deformed by an electron beam. This oil film, thanks to its variable birefringence, causes a variation in contrast in the projection optical beam. The Eidophore is the only system allowing video projection on a very large screen.

Plus répandus sont les projecteurs vidéo tri-tubes dans lesquels on projette, sur un écran de l'ordre du mètre carré, les images rouge, verte et bleue de trois tubes cathodiques très brillants.More widespread are the three-tube video projectors in which we project, on a screen of the order of a square meter, the red, green and blue images of three very bright cathode ray tubes.

Dans le même ordre d'idées, les panneaux modulaires à tubes à rayons cathodiques deviennent très utilisés dans le domaine de l'affichage publicitaire et commercial.In the same vein, modular cathode ray tube panels are becoming widely used in the field of advertising and commercial display.

Dans la famille des projecteurs à afficheurs à cristaux liquides, on connaît un système à trois afficheurs éclairés en rouge, vert et bleu respectivement, et comportant des miroirs dichroïques avec une lentille de projection.In the family of projectors with liquid crystal displays, a system is known with three displays lit in red, green and blue respectively, and comprising dichroic mirrors with a projection lens.

Enfin, certaines firmes proposent des panneaux modulaires à cristaux liquides couleur.Finally, some firms offer modular color liquid crystal panels.

Le document US-A- 3 750 136 divulgue un projecteur à afficheur à cristaux liquides.Document US-A-3,750,136 discloses a liquid crystal display projector.

Ces divers dispositifs présentent tous des inconvénients.These various devices all have drawbacks.

Les assemblages de tubes à rayons cathodiques ou d'afficheurs à cristaux liquides ont l'inconvénient de présenter un effet de "grille noire" dû à la jonction des divers modules. Ils ne sont pas adaptés à un affichage de qualité.The assemblies of cathode ray tubes or liquid crystal displays have the disadvantage of having a "black grid" effect due to the junction of the various modules. They are not suitable for quality display.

En outre, les modules à afficheur à cristaux liquides présentent une hétérogénéité de coloration due à l'utilisation de filtres mosaïques colorés multiples (un par écran). L'oeil étant très sensible aux variations de couleur, l'observateur distingue en général très nettement les variations de coloration d'un module à l'autre, lors de l'affichage de plages isochromes.In addition, the modules with liquid crystal display have a heterogeneity of coloring due to the use of multiple colored mosaic filters (one per screen). The eye being very sensitive to variations in color, the observer generally distinguishes very clearly the variations in coloring from one module to another, when displaying isochromic ranges.

Enfin, dans les afficheurs à cristaux liquides en couleur, qui sont utilisés dans ces modules, les filtres colorés sont situés à l'intérieur de la cellule pour éviter les effets de parallaxe ; en conséquence, ils s'échauffent sous fort flux lumineux, ce qui provoque une détérioration du contraste de l'afficheur.Finally, in color liquid crystal displays, which are used in these modules, the colored filters are located inside the cell to avoid the effects of parallax; as a result, they heat up under strong luminous flux, which causes a deterioration of the contrast of the display.

Dans les systèmes à projection utilisant trois afficheurs à cristaux liquides dédiés chacun à une couleur, cet inconvénient n'existe pas car le filtre monochrome est, cette fois, à l'extérieur de la cellule à cristaux liquides. Cependant, ce système est pénalisé par l'emploi de filtres dichroïques coûteux et l'obtention d'un rendement médiocre.In projection systems using three liquid crystal displays each dedicated to a color, this drawback does not exist because the monochrome filter is, this time, outside the liquid crystal cell. However, this system is penalized by the use of expensive dichroic filters and by obtaining poor performance.

Enfin, les projecteurs tri-tubes à rayons cathodiquesm ne sont adaptés qu'aux surfaces moyennes (de l'ordre du mètre carré) et sont de qualité médiocre du fait de la non-fixité spatiale de l'image du tube. La superposition des trois couleurs est généralement imparfaite.Finally, tri-tube cathode ray projectorsm are only suitable for medium surfaces (of the order of a square meter) and are of poor quality due to the spatial non-fixity of the image of the tube. The superimposition of the three colors is generally imperfect.

Seul le système Eïdophore est aujourd'hui adapté aux très grandes surfaces d'affichage. Mais il est très coûteux et nécessite une cabine de projection spécialisée.Only the Eidophore system is today suitable for very large display surfaces. But it is very expensive and requires a specialized projection booth.

La présente invention a justement pour but de remédier à ces inconvénients.The object of the present invention is precisely to remedy these drawbacks.

A cette fin, elle préconise le dispositif défini dans la revendication 1To this end, it recommends the device defined in claim 1

Bien que l'invention couvre le cas où l'on n'utiliserait qu'un seul module de projection, on préfère juxtaposer une pluralité de modules rangés en lignes et colonnes, les images correspondant à ces divers modules étant juxtaposées sur l'écran pour former une image unique.Although the invention covers the case where only one projection module is used, it is preferred to juxtapose a plurality of modules arranged in rows and columns, the images corresponding to these various modules being juxtaposed on the screen to form a unique image.

De préférence, l'afficheur à cristaux liquides est du type à matrice active ; il est par exemple à transistors en couches minces.Preferably, the liquid crystal display is of the active matrix type; it is for example with thin film transistors.

Dans le dispositif de l'invention, les afficheurs à cristaux liquides sont donc monochromes, ce qui évite la présence de filtres colorés à l'intérieur de l'afficheur et, par conséquent le risque de leur échauffement et leur dégradation. Les filtres colorés sont sur l'écran d'observation. Leur réalisation s'en trouve facilitée : disparition des contraintes liées à la compatibilité avec les cristaux liquides, et possibilité de dimensions plus grandes (éléments colorés de l'ordre du millimètre carré sur l'écran de projection) autorisant la réalisation par imprimerie.In the device of the invention, the liquid crystal displays are therefore monochrome, which avoids the presence of colored filters inside the display and, consequently, the risk of their heating and their degradation. Filters are on the observation screen. Their realization is thereby facilitated: disappearance of the constraints linked to compatibility with liquid crystals, and possibility of larger dimensions (colored elements of the order of a square millimeter on the projection screen) allowing production by printing works.

Les images projetées peuvent être raccordées au pixel près, grâce à un montage mécanique ajustable des modules de projection : les raccords entre les images modulaires projetées sont alors invisibles.The projected images can be connected to the nearest pixel, thanks to an adjustable mechanical mounting of the projection modules: the connections between the projected modular images are then invisible.

Enfin, le système de projection par l'arrière conduit à la conception d'écrans autonomes qui, grâce à un jeu de miroirs, peuvent être d'épaisseur faible, donc peu encombrants.Finally, the rear projection system leads to the design of autonomous screens which, thanks to a set of mirrors, can be of low thickness, therefore compact.

De toute façon, les caractéristiques de l'invention apparaîtront mieux à la lumière de la description qui suit. Cette description porte sur des exemples de réalisation de l'invention et se réfère à des dessins annexés sur lesquels :

  • la figure 1 montre une vue schématique en perspective d'un dispositif selon l'invention,
  • la figure 2 montre une vue de côté d'un dispositif selon l'invention,
  • la figure 3 montre la structure d'un module de projection,
  • la figure 4 montre la face arrière de l'écran de projection.
In any case, the characteristics of the invention will appear better in the light of the description which follows. This description relates to exemplary embodiments of the invention and refers to the accompanying drawings in which:
  • FIG. 1 shows a schematic perspective view of a device according to the invention,
  • FIG. 2 shows a side view of a device according to the invention,
  • FIG. 3 shows the structure of a projection module,
  • Figure 4 shows the rear face of the projection screen.

On voit sur les figures 1 et 2 un dispositif d'affichage géant selon l'invention. Ce dispositif comprend un écran E de très grandes dimensions, deux rangées de trois modules de projection MP, chacun associé à un premier miroir M1 et à un second miroir M2. L'ensemble est porté par un châssis 6 qui comprend des moyens de réglage non représentés pour l'ajustage initial des différents modules par rapport à l'écran.FIGS. 1 and 2 show a giant display device according to the invention. This device comprises a screen E of very large dimensions, two rows of three projection modules MP, each associated with a first mirror M1 and a second mirror M2. The assembly is carried by a chassis 6 which includes adjustment means, not shown, for the initial adjustment of the various modules with respect to on the screen.

Eventuellement, une cellule photosensible C (cf Fig. 2) mesure l'intensité lumineuse émise par chaque module et commande en conséquence le module correspondant pour obtenir l'intensité appropriée.Optionally, a photosensitive cell C (see Fig. 2) measures the light intensity emitted by each module and consequently controls the corresponding module to obtain the appropriate intensity.

La figure 3 illustre plus en détail la structure d'un module de projection. On y voit une source de lumière blanche S (lampe halogène ou à iodures métalliques), un condenseur asphérique C, une double lentille de Fresnel F, un premier polariseur P1, un afficheur à cristaux liquides A et une lentille de projection L. L'afficheur est situé dans le plan focal objet de cette lentille, l'écran E étant situé dans le plan image. Le second polariseur P2 est supposé être plaqué contre l'écran (cf Fig. 4).Figure 3 illustrates in more detail the structure of a projection module. We see a white light source S (halogen or metal halide lamp), an aspherical condenser C, a double Fresnel lens F, a first polarizer P1, a liquid crystal display A and a projection lens L. L ' display is located in the object focal plane of this lens, the screen E being located in the image plane. The second polarizer P2 is supposed to be pressed against the screen (see Fig. 4).

L'ensemble lampe-condenseur-double lentille de Fresnel a pour fonction d'éclairer l'afficheur A sous un angle obtus, afin que toute la lumière le traversant converge au centre de la lentille de projection L. On optimise ainsi le rendement lumineux. La lentille de projection L a une ouverture suffisante pour éviter toute aberration chromatique.The Fresnel lamp-condenser-double lens assembly has the function of illuminating the display A at an obtuse angle, so that all the light passing through it converges at the center of the projection lens L. This thus optimizes the light output. The projection lens L has a sufficient opening to avoid any chromatic aberration.

L'afficheur à cristaux liquides est de préférence du type à matrice active et à transistors à couches minces (TFT). Un procédé simple de réalisation d'un tel afficheur, ne nécessitant que deux niveaux de masquage et gravure, est décrit dans le document de brevet français FR-A-2 533 072.The liquid crystal display is preferably of the active matrix and thin film transistor (TFT) type. A simple method for producing such a display, requiring only two levels of masking and etching, is described in the French patent document FR-A-2 533 072.

Un tel afficheur conduit à un fort contraste, permet l'obtention de niveaux de gris et s'accommode d'une cadence compatible avec des signaux de télévision.Such a display leads to high contrast, makes it possible to obtain gray levels and accommodates a rate compatible with television signals.

Quant à l'écran, il peut être conforme à la figure 4. Il est situé au plan image de la lentille de projection et est constitué d'un supoprt transparent 10 (verre ou polycarbonate) ayant une face avant 12 dirigée vers l'observateur 0 et une face arrière 14. Cette dernière face est légèrement dépolie, afin de diffuser la lumière dans un angle de vision confortable (gain de l'écran inférieur à 6). Sur la face arrière 14 sont déposées des mosaïques de filtres colorés 16 dans trois couleurs primaires, R, V, B (rouge, vert, bleu par exemple), soit par un procédé d'impression direct ("offset" ou sérigraphie), soit par collage d'un film photographique couleur. Pour optimiser le contraste (qualité du noir) on peut réaliser, en plus des filtres colorés, une grille noire 18 de séparation entre les filtres (dite "Black Matrix").As for the screen, it can be in accordance with FIG. 4. It is located in the image plane of the projection lens and consists of a transparent supoprt 10 (glass or polycarbonate) having a front face 12 directed towards the observer 0 and a rear face 14. This last face is slightly frosted, in order to diffuse the light in a comfortable viewing angle (gain of the screen less than 6). On the rear face 14 are deposited mosaics of colored filters 16 in three primary colors, R, G, B (red, green, blue for example), either by a direct printing process ("offset" or serigraphy), or by collage of a color photographic film. To optimize the contrast (quality of the black), it is possible to produce, in addition to the colored filters, a black grid 18 for separation between the filters (called "Black Matrix").

On peut aussi coller sur l'écran d'observation l'un des deux polariseurs P2, nécessaires au fonctionnement des afficheurs à cristaux liquides. Il sert alors en plus de protection des filtres colorés.One can also stick to the observation screen one of the two polarizers P2, necessary for the operation of liquid crystal displays. It then serves in addition to protecting the color filters.

La répartition des pixels de l'afficheur à cristaux liquides est exactement celle des filtres colorés élementaires de l'écran. Dans le cas illustré, cette répartition est "triangulaire", ou si l'on veut, en quinconce. Les lignes d'adressage restent horizontales, comme d'ordinaire mais les colonnes d'adressage présentent des décrochements. Ainsi, chaque pixel de l'afficheur est projeté exactement sur l'un des filtres colorés de l'écran. Chaque afficheur est commandé pour que l'image projetée, qui n'est modulée qu'en intensité, fasse apparaître l'image souhaitée en couleur.The pixel distribution of the liquid crystal display is exactly that of the elementary color filters of the screen. In the illustrated case, this distribution is "triangular", or if desired, staggered. The address lines remain horizontal, as usual, but the address columns have notches. Thus, each pixel of the display is projected exactly on one of the colored filters of the screen. Each display is controlled so that the projected image, which is only modulated in intensity, shows the desired image in color.

A titre purement explicatif, on peut réaliser des afficheurs à cristaux liquides de 7 cm x 9 cm avec un pas de 250µm ; on peut utiliser un grandissement de 10, ce qui conduit à des images modulaires de 70 x 90 cm ; l'écran peut comprendre des filtres répartis au pas de 2,5 mm et présenter des dimensions de 1,4 m x 2,7 m ; il existe ainsi deux rangées de trois images modulaires ; une telle image comprend donc 560 lignes de 360 triades, soit 560 x 1080 pixels.For purely explanatory purposes, liquid crystal displays of 7 cm x 9 cm can be produced with a pitch of 250 μm; you can use a magnification of 10, which leads to modular images of 70 x 90 cm; the screen may include filters distributed in steps of 2.5 mm and have dimensions of 1.4 mx 2.7 m; there are thus two rows of three modular images; such a image therefore includes 560 lines of 360 triads, or 560 x 1080 pixels.

Claims (10)

  1. Giant display means incorporating a large screen (E) and at least one projection module (MP) using a liquid crystal display, said projection module (MP) comprising a white light source (S), a monochromatic liquid crystal display (A) placed between the source (S) and the rear face (14) of the screen (E) and optical means (L, C, F, P1, L') suitable for projecting the image of the display (A) onto the rear face (14) of the screen (E), each display being constituted by pixels, characterized in that the screen (E) is translucent and comprises a front face (12) directed towards the observer (O) and a rear face (14) incorporating a mosaic of colored filters (16) organized into trios of primary colors (R, V, B), each pixel being projected onto one of the various colored filters supported by the screen.
  2. Means according to claim 1, characterized in that it comprises various projection modules (MP) juxtaposed in rows and columns, the images corresponding to said modules being projected onto screen (E) and juxtaposed for forming a single image.
  3. Means according to claim 1, characterized in that the screen (E) is constituted by a transparent support (10), whose rear face (14) is matt.
  4. Means according to claim 1, characterized in that, on its rear face (14), the screen (E) comprises a black grid or matrix (18) for separating the colored filters (16).
  5. Means according to claim 1, characterized in that the liquid crystal display (A) is of the active matrix type.
  6. Means according to claim 5, characterized in that the active matrix display (A) is of the thin film transistor type.
  7. Means according to claim 1, characterized in that the colored filters (16) of screen (E) are distributed in the form of triangles (R, V, B) and the liquid crystal display (A) comprises pixels also organized in triangular form.
  8. Means according to claim 1, characterized in that each projection module (MP) comprises, in front of the light source (S), successively a condenser (C), a double Fresnel lens (L), a first polarizer (P1), a projection lens (L') with an object focal plane in which is placed the liquid crystal display (A), a first reflecting mirror (M1), a second reflecting mirror (M2) and a second polarizer (P2), the screen (E) being placed in the image plane of the projection lens (L').
  9. Means according to claim 8, characterized in that the second polarizer (P2) is placed against the rear face (14) of screen (E).
  10. Means according to claim 1, characterized in that it also comprises a means (C) for checking the light intensity projected by each projection module (MP) and a means for controlling on return said intensity at an appropriate value.
EP89401805A 1988-06-28 1989-06-26 Gigantic liquid crystal display Expired - Lifetime EP0349404B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8808663 1988-06-28
FR8808663A FR2633425B1 (en) 1988-06-28 1988-06-28 GIANT LIQUID CRYSTAL DISPLAY DEVICE

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EP0349404A1 EP0349404A1 (en) 1990-01-03
EP0349404B1 true EP0349404B1 (en) 1993-04-28

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DE68906209D1 (en) 1993-06-03
JPH0253095A (en) 1990-02-22
CA1321718C (en) 1993-08-31
DE68906209T2 (en) 1993-10-28
EP0349404A1 (en) 1990-01-03
FR2633425B1 (en) 1990-09-21
US5005950A (en) 1991-04-09
FR2633425A1 (en) 1989-12-29

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